Numerous of systems for controlling a lighting network based on a traffic monitoring are known, where the individual light sources or group consisting of plurality of light sources are switched off or switched on. The switching is often done by using some light sensors or timer, when controlling lighting network due to environmental parameters (light condition), or motion sensor or other suitable devices when the controlling is based on an active traffic loads on a road or other area. Reasons for controlling the lighting network includes among other to save energy, but also increasing lifetime of the equipment. Also use of demand responses of a smart grid is known in the outdoor lighting systems. Typically outdoor lighting demand response have two approaches, namely 1) use an alternative energy source or local energy storage when a demand response signal is received, or 2) shed load when a demand response signal is received.
The prior art document WO2013144756 relates for operation of a plurality of lighting units of a lighting network according to energy demand or energy supply. According to WO2013144756 a demand response of a smart grid may be proactively managed based on time intervals or the zone of the lighting units of the lighting network. An adjusting energy demand of the outdoor lighting network connected to a smart power grid is provided and includes the following steps: collecting first zone energy supply information and first zone load demand information of each of a plurality of first zone lighting units of the lighting network for each of a plurality of first zone subintervals; collecting second zone energy supply information and second zone load demand information of each of a plurality of second zone lighting units of the lighting network for each of a plurality of second zone subintervals; receiving electricity prices from a utility for a plurality of future first zone subintervals of the first zone subintervals and for a plurality of future second zone subintervals of the second zone subintervals; proactively adjusting a first zone light operation strategy of the first zone lighting units prior to the future first zone subintervals based on the first zone energy supply information, the first zone load demand information, and the electricity prices; and proactively adjusting a second zone light operation strategy of the second zone lighting units prior to the future second zone subintervals based on the second zone energy supply information, the second zone load demand information, and the electricity prices.
Another prior art document WO2011055259 is directed for a control system for an object-sensing lighting network, and for a control system for an outdoor lighting fixture that dynamically determines a relationship to a plurality of other lighting fixtures. The control system of a lighting fixture may dynamically determine its relationship to a plurality of other lighting fixtures along one or more normal paths of activity by monitoring travel times of an object between the lighting fixture and a plurality of other lighting fixtures during periods of low activity. WO2011055259 is not related to demand response, but each street lighting fixture node has a motion detector system in electrical communication with the controller of the light fixture node.
Further WO 2014/147510 A1 describes a light management information system for an outdoor lighting network (OLN) system, having a plurality of outdoor light units each including at least one sensor type, where each of the light units communicates with at least one other light unit, at least one user input/output device in communication with at one or more of said outdoor light units, a central management system in communication with light units, said central management system sends control commands and/or information to one or more of said outdoor light units, in response to received outdoor light unit status/sensor information from one or more of said outdoor light units or received user information requests from said user input/output device, a resource server in communication with said central management system, wherein the central management system uses the light unit status/sensor information and resources from the resource server to provide information to the user input/output device and/or reconfigure one or more of the lights units.
US 2010/262297 describes a solution, where lighting devices are configured to communicate with one another and with external systems. Sensors located at such lighting devices communicate with the external systems and with others of the lighting devices. Lighting is controlled to maintain safety, to drive customer traffic within a retail facility, or to conserve energy. An application programming interface provides a common mechanism for control of various lighting device types.
WO 2012/172470 describes a lighting system including at least one controller and a memory containing program portions which configure the controller to obtain weather forecast information including one or more of current and expected weather conditions over a period of time, and thereby determine one or more lighting settings based upon the weather forecast information.
In addition WO 2010/010493 A1 discloses a solution of setting up a luminaire, said luminaire being part of a network of luminaires and each luminaire of said network of luminaires being a node of a wireless communication network.
There are however some disadvantages relating to the known prior art, such as the controlling is very often limited to quite narrow area, the switching of the certain portion of the lighting network induced consumption peaks into the electric power grid, as well as continuous switching on and off or even dimming and brightening easily disturbs urban environments. In addition also lighting operating strategy is often changed at intervals of e.g. one day and at subintervals of one hour, whereupon the system does not react to real-time detection of road users. Thus, any dimming done by the prior art solutions degrades traffic safety. Moreover in the systems using motion detection the cost of installing and maintaining the dedicated motion detection electronics is very significant, and having such dedicated equipment implies that each system in a smart city that needs traffic monitoring data will have to have its own sensors.